Dirt Nap used to be a mutant with the ability to absorb and take on the form of others until he tried to absorb Wolverine, but couldn't due to Wolverine's strong healing factor.
Dirt Nap managed to escape by absorbing a rat and taking on its form, but found that he couldn't undo the transformation and, thus, was forced to remain a rat. He later joined the Dark Riders, led by Genesis, and later still teamed up with Chimera to attempt to get revenge on Wolverine, whom he blamed for his rodent state of body.
Both Chimera and Dirt Nap were assumed to have been killed in an implosion until they visited Emplate in his pocket dimension through a warp chamber (which appeared on Emplate's side as a door with the letters W.C. on it). The two villains, Emplate and Chimera, struck a deal and launched an attack on Generation X in a bid to regain what Emplate had lost but wanted so badly: a red-skinned mutant girl named Penance, his favorite snack.
Dirt Nap, meanwhile, resurfaced on the grounds of the Massachutts Academy where Generation X trained. A police chief named Chief Authier thought he'd shot the rat, but Dirt Nap was just playing possum. The talking rat then went along with Generation X to another dimension in an attempt to rescue their kidnapped teammate Synch.
Dirt Nap saved Generation X -- not to mention all beings in existence -- from M-Plate when his mouth opened to gigantic proportions and he swallowed M-Plate whole. M-Plate, however, didn't go down the right way and ended up giving Dirt Nap a fatally explosive case of indigestion.
Dirtnap has been proven unable to digest Wolverine due to his healing factor, in addition symbiotes Dirtnap has tried to "eat" such as Venom
, have proven impossible for Dirtnap to completely absorb. This suggests those with healing powers can not be consumed by Dirtnap.